The present invention relates to manufacturing methods, and more particularly, to methods for reducing surface roughness in internal passages of workpieces.
In manufacturing processes, there is a desire to reduce surface roughness in small internal channels of components. This is especially true for parts with complex internal geometries, for example components or assemblies made by casting or by additive manufacturing processes.
Various methods of reducing surface roughness are known such as mechanical polishing, electrochemical polishing, chemical passivation, and chemical polishing using strong acids. While all these methods are effective, each has disadvantages.
For example, mechanical polishing becomes difficult as internal passage dimensions shrink, and can produce uneven results around curves and other internal features due to variation in the flow field especially in “dead zones” of the flow field. Electrochemical polishing requires insertion of an electrode near the surface to be polished, which is not feasible on complex internal geometries. Chemical polishing using strong acids presents significant environmental, health, and safety challenges.
Accordingly, there remains a need for a method of reducing surface roughness in internal passages.